Field of the Invention
The present invention is related to epoxy resins. More particularly, the present invention is related to hardeners for epoxy resins.
Background of the Invention
This invention relates to new polyamide compositions and their use as hardeners for epoxy resins. The new polyamides are the reaction products of bis(2-(piperazin-1-yl)ethyl)amine (BPEA) with dimer and monomer fatty acids. The BPEA polyamides give faster cure rates with epoxy resins and the cured composition exhibits higher flexibility compared to standard polyamides made from polyalkyleneamines (e.g. triethylenetetramine (TETA)). In addition, the BPEA polyamide gives a lower onset cure temperature with epoxy resins than TETA polyamides. This allows the use of BPEA polyamides in lower temperature applications than is possible with standard polyamides. In coatings applications, the BPEA polyamides give better film appearance and do not require an induction time.
Another aspect of this invention relates to polyamide composition in which the polyamide is the reaction of excess amine mixture of BPEA and other polyamine with dimer and monomer fatty acids.
Another aspect of this invention is the use of BPEA polyamides as a modifier in epoxy thermosets. The BPEA polyamide can be blended with any other amine hardeners, e.g. TETA based polyamides, aliphatic amines (hexamethylenediamine), polyalkyleneamines (e.g. TETA), cycloaliphatic amines (e.g. isophoronediamine), aromatic amines (e.g. methylenedianiline), hererocyclicamines (e.g. aminoethylpiperazine), and aryl-aliphatic amines (e.g. m-xylenediamine), and the resulting blend can be used to cure epoxy resins. In this way, the reactivity of the formulation and final properties of the cured epoxy thermoset can be varied to meet the formulator's needs.